Brena, Sergio

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Brena
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Sergio
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2021 - 20234
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Now showing 1 - 4 of 4
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    Construction and Materials Best Practices for Concrete Sidewalks: Phase II - Long-Term Performance and Hot Weather Placement Effects
    (2023-01-01) Peterman, Kara; Brena, Sergio; Rudraraju, Likhitha; Shea, Brian
    This report summarizes the investigation of construction practices and materials to develop durable concrete sidewalks which can resist scaling damage caused by exposure to freezing environment and deicer application. Over 16 months, a field study accompanied by laboratory testing was conducted to identify factors that affect the performance and durability of sidewalks. The variables considered for the study are concrete mix design, placement and finishing practices, curing methods, and deicer application. The placement of the sidewalks took place in late July 2021, to investigate the impact of hot weather concreting practices on the performance of sidewalks. Forty-eight sidewalk panels were placed behind Robert Brack Structural Engineering Laboratory at University of Massachusetts Amherst (UMass). During the sidewalk placement, cylinders and rectangular prisms were placed for laboratory testing. Thirty-two rectangular prisms were subjected to same curing method as the corresponding sidewalks for scaling resistance test in laboratory via BNQ NQ 2621-900. The results of this study indicate that mixture design formulation, curing method, de-icing method, and temperature based concreting practices impact the performance of scaling in concrete sidewalks. Recommendations incorporating these variables are presented in this report with accompanying testing standards and procedures.
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    Construction and Materials Best Practice for Concrete Sidewalks
    (2021-01-01) Brena, Sergio F; Peterman, Kara; Sullivan, Rhyan
    This report summarizes an 18-month effort to investigate best practices to incorporate into the materials and construction of concrete sidewalks to mitigate surface scaling damage induced by freeze-thaw cycles in the presence of deicing chemicals. The study involved an in-situ experimental study accompanied by laboratory testing and quantitative analyses to determine key factors that impact sidewalk performance and durability. The primary variables considered in the study were concrete mixture design (aggregate/paste optimization, air content, and cementitious material replacements), workmanship (delivery, placement, finishing, curing), and deicing treatment. The collective effort involved participants from construction companies, a concrete producer, academia, testing laboratories, and the Massachusetts Dept. of Transportation (MassDOT). Fifty-four unique sidewalk panels were placed adjacent to the Hopkinton, MA, MassDOT Research and Materials Laboratory. Collectively, the results indicate that sidewalk performance can be controlled though a combination of optimized mix design formulation, proper pre-placement, placement, finishing, curing, cold and hot weather concreting practices, contractor quality control, and department acceptance. Recommendations based on findings and in combination with referenced standards are provided, covering the range of variables studied in this research
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    Ultra-High-Performance Concrete Reinforced with Multi-Scale Hybrid Fibers and Its Durability-Related Properties
    (2023-01-01) Wei, Jianqiang; Brena, Sergio; Ritchie, Cameron; Bhaskar More, Hitesh
    Due to its excellent mechanical properties, dense microstructure, low permeability, ease of placement and volume stability, ultra-high performance concrete (UHPC) is considered the next-generation structural concrete and is increasingly used in transportation infrastructure. While previous research efforts generated valuable results, to achieve the desired performance, UHPC needs to be well formulated with precise and optimized quantities of cementitious materials, fillers, fine aggregate, water, chemical admixtures, and fibers. In addition, the mixture design of UHPC and its correlation with the performance evolution under different curing conditions remain unclear, and there exist critical significant gaps in understanding the efficiency of fibers and mixture design on the properties of UHPC, especially the mechanical and durability-related performance. Massachusetts Department of Transportation (MassDOT) is exploring multiple infrastructure applications that can incorporate UHPC, including joints, overlays, repairs, rehabilitation, and bridge beam fabrication. This project aims to develop UHPC mix design formulations that can be implemented at ready-mix batching plants or precast/prestressed concrete fabrication facilities by identifying and maximizing the roles of fibers and additives in enhancing mechanical and durability-related properties. Four fiber-reinforced mixes and seven UHPC mixes with different fibers were investigated and a UHPC mix for large-scale batching and field applications was recommended.
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    Revised Load Rating Procedures for Deteriorated Prestressed Concrete Beams
    (2023-01-01) Stripsky, Alex; Brena, Sergio F; Boakye, Jessica; Civjan, Scott A; Gerasimidis, Simos
    The first prestressed concrete bridge in the United States was built in the early 1950s. Since then, several typical sections have been developed for use in bridge construction including I-beams, deck slabs, box beams, double tees, etc. In bridges under aggressive environments, corrosion deterioration of prestressing strands and stirrups has occurred creating challenges associated with determining the strength of deteriorated existing bridge sections. The MassDOT LRFD Bridge Manual includes provisions to estimate strength of corrosion deteriorated prestressed concrete box beams allowing engineers to calculate the load rating of these types of bridges. The provisions are based on the observed condition of the bridge, particularly with regard to estimates of strand area reductions to estimate residual strength. In bridges with adjacent box beams or deck slabs, corroded reinforcement is difficult to identify because only the top and bottom surfaces of the superstructure elements are accessible. The goals of this research are to evaluate the existing strength calculation procedures and to provide recommendations on how to properly evaluate the reduction in strand area based on the observed condition of the bottom surface of the prestressed box or deck beams.